Arthroplasty revision device and method

ABSTRACT

A surgical instrument for revising/removing an artificial disc or removing/replacing a core of an artificial disc includes a pair of tips, each tip having a pair of tines and a stop defining a proximal end of each tine. The stop of at least one tip is abutted against an interior surface of an implanted endplate of an artificial disc, whereby tines of the tip can support the artificial disc. The tip is separated from another, opposing tip, whereby opposing implanted endplates, each of which is supported by pairs of tines of a tip, are separated, thereby distracting vertebrae between which the endplates are implanted. Upon distracting the disc space, the core can be revised or removed from between the endplates of the artificial disc. Following core removal, the endplates of the artificial disc are revised (repositioned), removed or replaced.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/263,603, filed on Oct. 31, 2005 and entitled “Arthroplasty RevisionDevice and Method,” which is hereby incorporated by reference in itsentirety.

BACKGROUND OF THE INVENTION

Arthroplasty is becoming significantly more prevalent as a surgicalprocedure to treat injury and disease. Of particular importance is theuse of artificial discs to replace vertebral discs as functioningartificial joints.

Instrumentation employed to conduct surgical techniques that implantartificial discs still are of limited variety and generally do notpermit modification subsequent to completion of the procedure withoutradical reconstruction and a significant likelihood of additional tissuedamage. Artificial discs typically include two endplates and a corebetween endplates. The core permits movement of the endplates relativeto each other, thereby simulating the function of the intervertebraldisc that it replaces. Artificial discs can be implanted as completeassemblies, or, alternatively, endplates of an artificial disc can beinserted first, followed by placement of a core between the endplates.As in any surgical implantation, the initial placement may not beoptimal. In such an instance, the surgeon typically is left with theoption of leaving the implant in a sub-optimal position or removing it,and replacing the implant in a more optimal position. During theprocess, further traumatization of the surrounding tissue can occur.Therefore, a need exists for a device and a method that significantlyeliminates or reduces the above-referenced problems.

SUMMARY OF THE INVENTION

The invention is directed to a surgical instrument and a method forrevising/removing an artificial disc or removing/replacing a core of anartificial disc.

In one embodiment, a surgical instrument of the invention includes apair of tips, each tip having a pair of tines and a stop defining aproximal end of each tine. In one embodiment, the stop of each tipextends between the tines of the tip. The tines of each tip also canessentially match the tines of the other tip. In one embodiment, thetines of each tip have a flat surface, and the flat surface of the tinesof each tip are parallel. Alternatively, the tines of each tip can havesurfaces that complement surfaces of the tines of the other tip. In onesuch embodiment, each tip includes a base portion, wherein the tines ofeach tip extend from the base portion. Also, the base portion of eachtip can include a surface, at least a portion of which complements atleast a portion of a surface of a base portion of the other tip. In oneembodiment, the complementary surfaces of the base portion arecontinuous with the complementary surface of at least one tine of eachtip. The continuous complementing surfaces of the tips can partition theremaining portion of the base of each tip when the complementarysurfaces of the tips are in contact with each other.

In one embodiment, the surgical instrument includes a forceps portion.In one embodiment, the forceps portion is a double-action forceps. Inanother embodiment, the forceps portion is a parallel-action forceps.The tips can be releasable from the forceps portion. In one embodiment,at least one of the tips is releasable by activation of a spring-loadedclip that releasably couples the tip to the forceps portion. In aspecific embodiment, a major axis of the tines extends at an obliqueangle to a major axis of the forceps portion. The base of at least oneof the tips can define a chamfered recess having a major axisessentially parallel to a major axis of the tines of the tip. In aspecific embodiment, both tips can define a chamfered recess, whereinthe chamfered recesses are opposed to each other when the tips arecoupled to the forceps portion. In a particular embodiment, thecontinuous step of at least one tip is chamfered.

A method of revising a position of an artificial disc or of implanting acore of an artificial disc includes abutting the stop of at least onetip against an outer surface of an implanted endplate of the artificialdisc, whereby tines of the tip can support the artificial disc. The tipis then separated from another, opposing tip, whereby opposing implantedendplates, each of which is supported by a pair of tines of a tip, areseparated, thereby distracting vertebrae between which the endplates areimplanted. The core between the endplates can then be removed andreplaced by one that is more appropriately sized (e.g., height of thecore), or the core can be removed so that the endplates can be removedand easily repositioned (revised) or replaced. In a specific embodiment,the stops of each pair of tips abuts each of a pair of opposingimplanted endplates. In one embodiment, the tips are abutted against theendplates simultaneously. The tips can be abutted against the endplateswhile the tips are in a nested position. In one embodiment, the tips areseparated from each other by actuating nonparallel-action forceps towhich the tips are attached or of which they are a component. In anotherembodiment, the tips are separated from each other by actuating aparallel-action forceps to which the tips are attached or of which theyare a component. The method can further include the step of releasingthe forceps, whereby the endplates each rest against the core.

The present invention has many advantages. For example, the apparatusand method of the invention permit revision or implantation of a core ofan artificial disc without disturbing seating of implanted endplates ofthe artificial disc. Accordingly, the surgeon can conduct any necessaryiterative procedure that may be required to optimally place a corebetween implanted endplates of an artificial disc. Further, implantedendplates can be distracted with minimal movement, thereby alsominimizing trauma to adjacent tissue. Also, abutting stops of the tinesof each tip against an endplate enables the apparatus to be freelymanipulated by the surgeon without significant risk of injury byincidental contact of the tines, such as by contact of the tines tonerve tissue.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1A is a perspective view of a pair of tips of a surgical instrumentof the invention.

FIG. 1B is an end view of the pair of tips shown in FIG. 1A.

FIG. 1C is an opposing end view of the pair of tips shown in FIG. 1A.

FIG. 2A is a perspective view of FIGS. 1A-1C in a nearly-nestedposition.

FIG. 2B is an end view of the pair of tips in the nearly-nested positionshown in FIG. 2A.

FIG. 2C is a detail of the end view of FIG. 2B, showing the tines of thepair of tips nearly nested.

FIG. 2D is an opposing end view of the pair of tips shown in FIG. 2A inthe nearly-nested position.

FIG. 2E is an alternative embodiment of the surgical instrument of theinvention wherein the pair of tips abut each other at flat surfaces.

FIG. 3A is a perspective view of the pair of tips of FIGS. 1A-1C and2A-2D in combination with a parallel-action forceps in a refractionposition and of the relation of the pair of tips to the parallel-actionforceps upon assembly.

FIG. 3B is a side view of the embodiment shown in FIG. 3A.

FIG. 3C is a perspective view of the embodiment of FIGS. 3A and 3B in adistracted position.

FIG. 3D is a side view of the embodiment of FIG. 3C in the distractedposition.

FIG. 3E is a plan view of the embodiment of FIG. 3C.

FIG. 3F is an end view of the embodiment of FIG. 3C.

FIG. 4 is a perspective view of the pair of tips of FIGS. 1A-1C and2A-2D in combination with a nonparallel-action forceps in a retractionposition.

FIG. 5A is a perspective view of the invention in a refracted positionwhere tips are non-modular components of parallel action forceps.

FIG. 5B is a side view of the embodiment shown in FIG. 5A.

FIG. 5C is an end view of the embodiment shown in FIG. 5A.

FIG. 5D is a perspective view of the embodiment of FIG. 5A in adistracted position.

FIG. 5E is a side view of the embodiment of FIG. 5D.

FIG. 5F is an end view of the embodiment of FIG. 5D.

DETAILED DESCRIPTION OF THE INVENTION

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention.

The invention generally is directed to a surgical instrument and methodfor revising the position of, or implanting a core between, implantedendplates of an artificial disc. FIGS. 1A, 1B and 1C representperspective and opposing end views of pair of tips 10 of the surgicalinstrument of the invention in a distracted position. Tip 12 andopposing tip 14 include pairs of tines 16, 18 and 20, 22, respectively.Tines 16, 18 of tip 12 and tines 20, 22 of opposing tip 14 are eachdefined by stops 24, 26 and stops 28, 30, respectively.

Tip 12 and opposing tip 14 include base 32 and base 34, respectively. Asshown in FIG. 1A, stops 24, 26 of tip 12 are continuous along base 32.In corresponding manner, stops 28, 30 define a continuous surface alongbase 34 of opposing tip 14. Tines 16, 18 of tip 12 and tines 20, 22 ofopposing tip 14, along with a portion of base 32 and base 34, definecomplementary surfaces 36, 38 of tip 12, and complementary surfaces 40,42 of opposing tip 14. Specifically, complementary surface 36 nests withcomplementary surface 40 and complementary surface 38 nests withcomplementary surface 42. As shown in FIG. 1B, tip 12 and opposing tip14 also include chamfered surfaces 43, 44, at base 32 and base 34,respectively. As shown in FIG. 1C, tips 12, 14 also include recessedportions 46, 48, which define chamfered recesses 50, 52, respectively.Chamfered recesses 50, 52 oppose each other when complementary surfaces36, 40 and 38, 42 are nested. Chamfered recesses 50, 52 each include amajor axis that is essentially parallel to a plane extending through atleast one tine of a respective tip. Chamfered recesses 50, 52 areintended to allow access to space between tines during coreremoval/replacement.

Modular connectors 54, 56 extend from base 32 and base 34, respectively.A major axis of each of modular connectors 54, 56 extends through amajor axis of at least one tine and a respective tip at an obliqueangle. Preferably, the oblique angle is in a range of between about 1degree and about 20 degrees. In a particularly preferred embodiment, theoblique angle is 15 degrees. In the alternative, a major axis of thetines is parallel to the major axis of the forceps, or distractioninstrument.

FIGS. 2A, 2B and 2D represent perspective and opposing end views of thesurgical instrument of the invention shown in FIGS. 1A-1C in anearly-nested or nearly-reduced position. Tip 12 and opposing tip 14 arenearly-nested, because, as can be seen in FIG. 2C, which is a detail ofFIG. 2B, complementary surfaces 38, 42 of tines 18, 22, respectively,are not in contact, but are in close proximate relation to each other.Upon contact, tip 12 and opposing tip 14 would be in a nested position.It is to be understood, however, that as an alternative to complementarysurfaces, tines of opposing tips can abut without being complementary.In one embodiment, the tines of opposing tips can abut in a retractedposition at continuous flat surfaces of the tines, as shown in FIG. 2E(in a distracted position).

FIGS. 3A and 3B represent, respectively, perspective and side views ofsurgical instrument 60 of the invention that includes parallel-actionforceps 62 in combination with tip 12 and opposing tip 14 of FIGS. 1A-1Cand FIGS. 2A-2D. Parallel-action forceps 62 can be any suitableparallel-action forceps, such as is described in U.S. Pat. No.5,122,130, issued to Keller on Jun. 16, 1992, the entire teachings ofwhich are incorporated herein by reference. Tips 12 and 14 can bemodular, whereby they are releasable from another component of asurgical instrument. As shown in FIGS. 3A and 3B, tip 12 and opposingtip 14 are compatible for coupling with parallel-action forceps 62 atmodular connectors 54, 56. Modular connectors link with theparallel-action forceps with spring-loaded clips 64, 66, respectively.It is to be understood, however, that any suitable coupling mechanismcould be employed, such as described in U.S. Ser. No. 10/616,506, filedJul. 8, 2003, and U.S. Ser. No. 10/959,598, filed Oct. 6, 2004, theentire teachings of both of which are incorporated herein by reference.FIGS. 3A and 3B represent surgical instrument 60 in a reduced position.FIGS. 3C, 3D, 3E and 3F represent surgical instrument 60 in a distractedposition, with tip 12 and opposing tip 14 assembled with parallel-actionforceps 62. Alternatively, tip 12 and opposing tip 14 can be a componentof or suitably connected such as by a modular connection as described,for example, above, to a nonparallel-action forceps as opposed to aparallel-action forceps. A representative example of anonparallel-action forceps is shown in FIG. 4, wherein surgicalinstrument 70 includes nonparallel-action forceps 72 coupled to tip 12and opposing tip 14. In another embodiment, tip 12 and tip 14 can benon-modular components of parallel action or non-parallel actionforceps. FIG. 5A is a perspective view of tip 12 and tip 14 ascomponents of parallel action forceps 80 arranged as a non-modularembodiment in a retracted position. FIGS. 5B and 5C are side and endviews, respectively, of the non-modular embodiment of FIG. 5A. FIGS. 5D,5E and 5F are perspective, side and end views, respectively, of theembodiment of FIG. 5A in a distracted position.

In a method of the invention, the size of a core of an artificial discis revised, or the core of an artificial disc is implanted, by abuttingthe stop or stops of at least one tip of the invention against aninterior surface of an implanted endplate of an artificial disc, wherebytines of the tip can support the artificial disc. The tip is separatedfrom another opposing tip, whereby opposing implanted endplates, each ofwhich is supported by pairs of tines of a tip, are separated, therebydistracting vertebrae between which the endplates are implanted.Preferably, the stops and the tines of each tip comport with eachendplate, whereby the force of distraction of the vertebrae is born, atleast substantially, if not entirely, by the endplates, rather than bythe force of direct contact between the vertebrae and the tines. Uponsufficient distraction of the vertebrae, the core between the artificialdisc can be revised or the core can be removed, implanted, or both,between the endplates of the artificial disc. Preferably, the tips areabutted against the endplates while the tips are in a nested position.Actuation of the nonparallel-action forceps or parallel-action forcepsmoves the forceps from a reduced position, such as in shown in FIGS. 3Aand 3B, in the case of parallel-action forceps, to a distractedposition, such as is shown in FIGS. 3C through 3F, thereby distractingvertebrae adjacent to implanted endplates of an artificial disc. Inanother embodiment of the method of the invention, the core can beremoved, followed by removal of the pair of tips from between theendplates, and revision (repositioning), removal and/or replacement ofthe endplates of the artificial disc. The endplates can then bedistracted again by use of the pair of tips, as described above, and acore, of either the same or a different size can be implanted betweenthe endplates. The pair of tips is then removed by releasing theforceps, and the operation is completed.

While this invention has been particularly shown and described withreference to various embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the scope of the invention encompassed bythe appended claims.

1. A method for manipulating an artificial disc, comprising: a) abuttingthe stop of at least one tip against an outer surface of an implantedendplate of the artificial disc, whereby tines of the tip support theartificial disc; and b) separating the tip from another, opposing tip,whereby opposing implanted endplates, each of which is supported by apair of tines of a tip, are separated, thereby distracting vertebraebetween which the endplates are implanted, thereby manipulating theartificial disc.
 2. The method of claim 1, further including the step ofremoving or replacing a core of the artificial disc.
 3. The method ofclaim 2, wherein the core is removed, and further including the step ofrevising at least one of the endplates.
 4. The method of claim 3,wherein the core is removed and further including the step of replacingat least one of the endplates of the artificial disc.
 5. The method ofclaim 3, wherein the core is replaced with a core of different size. 6.The method of claim 1, wherein the stop of each of a pair of tips abutseach of a pair of opposing implanted endplates.
 7. The method of claim6, wherein the tips are abutted against the endplates simultaneously. 8.The method of claim 7, wherein the tips are abutted against the endplatewhile the tips are in a nested position.
 9. The method of claim 8,wherein the tips are separated from each other by actuating adouble-action forceps to which the tips are attached or of which theyare a component.
 10. The method of claim 8, wherein the tips areseparated from each other by actuating a parallel-action forceps towhich the tips are attached or of which they are a component.
 11. Themethod of claim 10, further including the step of releasing the forceps,whereby the endplates each rest against the core.